Due to these differences, KGs and relational DBs are applied in different settings.
KGs are mainly used to store Web-scale open-domain KBs, such as Freebase [1]} and DBPedia [2]}, where there are many variations in relations (or predicates) among entities, and users can issue complex questions which need to be parsed to map to different paths in the knowledge graph to retrieve the answer nodes.
Relational DBs, on the other hand, are widely used to store task-specific KBs where the attributes of entities can be pre-defined. For example, the KBs of many task-oriented dialog systems,
such as the ones designed for movie ticket booking or table reservation in a restaurant, are stored using relational DBs.
